Method for producing an improved cutting oil



United States Patent PRODUCING AN IMPROVED CUTTING OIL Joseph A. Smith,Baltimore, Md., assignor to Esso Research and Engineering Company, acorporation of Delaware No Drawing. Application April 20,1955, SerialNo. 502,738

5 Claims. (Cl. 252-331) METHOD FOR This invention relates to a metalworking lubricant and more particularly relates to the method for makingthe same. Still more particularly the invention relates to a method forproducing an improved cutting oil by .sulfonating, sulfurizing and thenlime neutralizing and dehydrating a naphthenic-base mineral lubricatingoil.

Cutting oils are used to perform several important functions in metalworking operations. They act to provide lubrication between the tool andthe work and also to dissipate heat and thus prevent overheating ofeither the tool or the work. By reason of these effects they reduce thepower consumed, increase the life of the tools, and provide smoother andmore perfect surfaces on the work. Numerous different types ofcompositions have been proposed heretofore for cutting oils. However,they have not been entirely satisfactory in all respects.

It has now been found that an improved cutting oil may be produced bysulfonating, sulfurizing and then lime neutralizing and dehydrating anaphthenic-base mineral lubricating oil, the several steps being carriedout at relatively low temperatures. More particularly the method of thepresent invention comprises treating a naphthenic-base minerallubricating oil with about to 50 pounds of HzSOi/barrel of oil at atemperature in the range of about 70 to 120 F., treating the resultantsulfonated oil with sulfur at a temperature in the range of about 80 to150 F., until about 0.5 to 1.5% by weight of sulfur, based on thesulfurized product has been added to said sulfonated oil, andneutralizing the resultant sulfonated and sulfurized oil with a basicreacting compound of calcium. The preferred basic reacting compound ofcalcium is calcium hydroxide. After the neutralization step the treatedoil is dehydrated, preferably by air blowing, at a temperature in therange of about 150 to 200 F. In the method of the present inventioncalcium naphthenates and calcium sulfonates are formed in situ in thelubricating oil.

The naphthenic-base mineral lubricating oils useful for the purposes ofthe present invention have a viscosity in the range of about 100 to 315SSU at 100 F., and preferably a viscosity in the range of about 175 to185 SSU at 100 F. In addition the lubricating oils have a naphthenicacid content in the range of about 0.8 to 1.5% by weight and preferablyabout 0.9 to 1.0% by weight. Such naphthenic base lubricating oils maybe obtained as distillates from Mid-Continent and South American crudeoils.

The first step in the manufacture of the cutting oils of the presentinvention is sulfonation. In this step the naphthenic-base lubricatingoil is treated at a temperature in the range of about 70 to 120 F.,preferably 80 to 100 F., with about 10 to 50, and preferably 20 to 30pounds of H2SO4/b31'l'6l (42 gallons) of oil. Preferably 98%concentrated sulfuric acid is employed although it will be understoodthat lesser strength sulfuric acids or turning sulfuric acid may beemployed if desired. The sulfonation is preferably carried out with iceing it with about 0.5 to 1.5 wt. percent, preferably about 0.8 to 1.2wt. percent, of sulfur at a temperature in the range of about to 150 F.,preferably to F. The sulfurization may be conveniently accomplished byadding the sulfur to the sulfonated oil and air agitating the mixturefor about 5 to 20 hours, preferably about 10 to 12 hours, at atemperature of 80 to F.

Thereafter the sulfonated and sulfurized oil is neutralized with a basicreacting compound of calcium. The preferred calcium compound is calciumhydroxide although it will be understood that calcium oxide or othercompounds of calcium may be used if desired. The treated oil is thenblown with air or other gaseous material until the oil composition isdehydrated. This air blowing step will generally require about 6 to 10hours and is carried out at a temperature in the range of about 150 to200 F., preferably in the range of to 180 F. Dehydration will beindicated by the oil composition changing from a milky appearance to abright clear oil composition. 7 The resultant finished cutting oil ofthis invention is used as such in cutting operations and is not of thetype known as a soluble oil or an emulsifiable oil. It will beunderstood that, if desired, conventional additives may be added to thecutting oil of this invention, such as corrosion inhibitors, e. g.propylene diamine, sorbitan monooleate, etc.; extreme pressure agents,e. g. sulfurized sperm oil or sulfurized lard oil; and the like.

The following examples are intended to set forth the invention ingreater detail as well as to show the superiority of the present cuttingoil over other lubricant compositions:

EXAMPLE I Three different lubricant compositions were prepared asfollows:

Lubricant composition of present invention Composition A.-A distillateobtained from a Venezuelan crude oil and having the following propertieswas used as the naphthenic-base lubricating oil for preparing thiscomposition:

Property:

Naphthenic acids, wt. percent 0.924 Viscosity, SSU at 100 F 180.3 APIgravity 21.3 Neutralization No 2.08

I carried out at a temperature in the range of 110 to 120 -180 F. untilbright.

Other lubricant compositions Composition B.--A distillate obtained froma Venezuelan crude oil and having the following properties was employedas a naphthenic-base lubricating oil to prepare this composition:

Property:

Naphthenic acids, wt. percent 0.995 Viscosity, SSU at 100 F 158 APIgravity 21.9 Neutralization No 2.24

The above-described naphthenic-base lubricating oil was mixed with 1.2%by weight of sulfur and the mixture was air agitated for hours tothoroughly incorporate this sulfur into the oil. This sulfurization wascarried out at a temperature in the range of l10-l20 F.

Composition C.--A distillate obtained from a Venezuelan crude oil andhaving the same properties as the distillate used to prepare compositionA was employed as the naphthenic-base lubricating oil to prepare thiscomposition. The naphtheniobase lubricant was acid treated andsulfurized under conditions identical to those described for compositionA. The resultant sulfonated and sulfurized product in this case howeverwas then neutralized with a Baum solution of sodium hydroxide afterwhich the oil was heated to 170-180" F. and washed with water to removesodium naphthenates and sodium sulfonates therefrom. Thereafter thecomposition was blown with air for 8 hours at 170-180 F.

The three lubricant compositions described above were then evaluated forcutting performance in the Almen machine shock test, which test isemployed to evaluate the relative cutting characteristics of cuttingoils. This test is carried out as follows: Shock tests are usually runon oils which carry the full load of 15 wts., gradual loading. Incarrying out the shock test, the Almen machine is set up with a new pinand bushings for each run with the test lubricant in the holder. Themachine is operated without a load for a 30'second break-in. Prior tothe 30-second break'in, a number of the two pound weights are placed onthe lever loading area and are held up by hand so that no load is on thebearing. As soon as the 30-second break-in period is completed, theentire load is lowered on the test piece and allowed to run for 10seconds. Individual runs are continued with new pin and bushings andwith increasing loads until the maximum load is reached which will notcause failure of the pin.

The following results were obtained in the Almen machine shock test:

Almen weights carried Composition (shock loading) 1 Composition ofpresent invention.

It will readily be seen that the cutting oil of the present invention(composition A) demonstrated superior performance in this test ascompared to the other two lubricant compositions (compositions B and C).

EXAMPLE II A distillate obtained from a Venezuelan crude oil and havingthe following properties was employed as the This naphthenic-baselubricating oil was employed to prepare the following two compositions:

Composition D.This composition was prepared in accordance with thisinvention. The naphthenic-base lubricating oil was treated with twodumps of 15 pounds (per barrel of oil) each of 98% H2504 followed by 1.5hours of air agitation and 16 hours of settling. The acid sludgesettling out was removed. Thereafter 0.8% by weight of sulfur was addedto the sulfonated oil and the mixture was air agitated for 12 hours atabout F. to thoroughly incorporate the sulfur into the oil. Theresultant sulfonated and sulfurized product was then neutralized withcalcium hydroxide and the neutralized product was blown with air at atemperature of about 170 F. for 6 hours.

Composition E.-The naphthenic-base lubricating oil in this case wassulfonated, neutralized and air blown in the same manner as wascomposition D, but the sulfurization step was omitted. This compositionwas thus not prepared in accordance with the present invention.

The two above-described lubricant compositions had the followingproperties and gave the following results in the Almen machine test:

1 Composition of present invention.

2 Defined as sulfur reacting with powdered copper.

The cutting oil produced in accordance with the present invention(composition D) is substantially superior in the Almen machine test tothe other lubricant composition (composition E). in addition, it hasbeen found that the cutting performance of composition D is better thanseveral commercially available sulfurized cutting oils of higher sulfurcontent. Composition D has also been found to be more stable at lowtemperatures than these high sulfur content commercially availablecutting oils, thereby eliminating undesirable sulfur separation. It willalso be noted that the viscosity of the treated oils (compositions D andE) are higher than the original naphthenic-base oil. This advantage isunexpected since generally when a lubricating oil distillate is acidtreated its viscosity after acid treatment is lower. However, due to thelow temperature acid treatment of the present invention, the viscosityincreases rather than decreases.

What is claimed is:

l. A method for producing an improved cutting oil which comprisestreating a naphthenic-base mineral lubrieating oil containing in therange of about 0.8 to 1.5% by weight of naphthenic acids with about 10to 50 pounds of HzSOr/barrel of oil at a temperature in the range ofabout 70 to F., treating the resultant sulfonated oil with about 0.5 to1.5% by weight of sulfur, based on the resultant sulfurized product, ata temperature in the range of about 80 to F., neutralizing the resultantsulfonated and sulfurized oil with a basic reacting compound of calcium,and dehydrating the resultant neutralized product at a temperature inthe range of about 150 to 200 F.

2. Method according to claim 1 wherein said basic reacting compound ofcalcium is calcium hydroxide.

3. Method according to claim 1 wherein said dehydrating step is carriedout by blowing said neutralized product with air.

4. A method for producing an improved cutting oil which comprisestreating a naphthenic base mineral lubricating oil containing 0.9 to1.0% by weight of naphthenic acids with about 20 to 30 pounds ofHzSOr/barrel of oil at a temperature in the range of about to F., 5. Acutting oil prepared according to the method of treating the resultantsulfonated oil with about 0.8 to claim 1.

1.2% by weight of sulfur, based on the resultant sulfurized product, ata temperature in the range of about References Cited in the file of thisPatent 100 to F., neutralizing the resultant sulfonated and 5 UNITEDSTATES PATENTS sulfurized oil with calcium hydroxide, and blowing theresultant neutralized product with air at a temperature 2367470 Neely et1945 2 392 891 Wallace et al Ian. 15 1946 1n the range of about to F.until the product is substantially dehydrated. McNab et a1 P 1947

1. A METHOD FOR PRODUCING AN IMPROVED CUTTING OIL WHICH COMPRISESTREATING A NAPHTHENIC-BASE MINERAL LUBRICATING OIL CONTAINING IN THERANGE OF ABOUT 0.8 TO 1.5%% BY WEIGHT OF NAPHTHENIC ACIDS WITH ABOUT 10TO 50 POUNDS OF H2SO4/BARREL OF OIL AT A TEMPERATURE IN THE RANGE OFABOUT 70* TO 120*F., TREATING THE RESULTANT SULFONATED OIL WITH ABOUT0.5 TO 1.5% BY WEIGHT OF SULFUR, BASED ON THE RESULTANT SULFURIZEDPRODUCT, AT A TEMPERATURE IN THE RANGE OF ABOUT 80* TO 150*F.,NEUTRALIZING THE RESULTANT SULFONATED AND SULFURIZED OIL WITH A BASICREACTING COMPOUND OF CALCIUM, AND DEHYDRATING THE RESULTANT NEUTRALIZEDPRODUCT AT A TEMPERATURE IN THE RANGE OF ABOUT 150* TO 200*F.